ES2709201T3 - A method of mitigating the formation of HCF-245cb during the hydrofluorination of HCFO-1233xf in HCFC-244bb - Google Patents

Abstract

A method of minimizing the formation of 1,1,1,2,2-pentafluoropropane in a liquid phase reaction of 2-chloro-3,3,3-trifluoropropene and HF in the presence of a hydrofluorination catalyst, comprising: (a) reacting HF with a sufficient amount of 2-chloro-3,3,3-trifluoropropene in the presence of a hydrofluorination catalyst under conditions effective to form 2-chloro-1,1,1,2-tetrafluoropropane, the hydrofluorination catalyst present in amounts sufficient to catalyze said reaction, and 2-chloro-1,1,1,2-tetrafluoropropane is formed with both a conversion of 80% or more and the selectivity of 1,1,1,2, 2-pentafluoropropane is 20% or less; and (b) maintaining the 2-chloro-1,1,1,2-tetrafluoropropane formed with both a conversion of 80% or more and a selectivity of 1,1,1,2,2-pentafluoropropane of 20% or less. adding said hydrofluorination catalyst continuously or periodically to the reactor in small increments.

Description

DESCRIPTION

A method of mitigating the formation of HCF-245cb during hydrofluorination of HCFO-1233xf in HCFC-244bb

Field of the invention

The present invention relates to an improved process for the manufacture of 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb), and more particularly to an improved process for the production of HCFC-244bb from the reaction of 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) and hydrogen fluoride in a reaction vessel in the liquid phase in the presence of a hydrofluorination catalyst in the liquid phase. HCFC-244bb is an intermediate compound in the production of 2,3,3,3-tetrafluoropropene (HFO-1234yf), which is a molecule with a low global warming potential.

Background of the invention

It is now known that hydrofluoroolefins (HFOs), such as tetrafluoropropenes (including 2,3,3,3-tetrafluoropropene (HFO-1234yf)), are effective refrigerants, heat transfer media, propellants, foaming agents, agents expansion, gaseous dielectrics, sterilizing supports, polymerization media, particle separation fluids, support fluids, abrasive polishing agents, displacement drying agents and working cycle power fluids. Unlike chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), which potentially damage the Earth's ozone layer, HFOs do not contain chlorine and, therefore, do not represent a hazard to the ozone layer. It has been shown that HFO-1234yf is a low global warming compound with low toxicity and, therefore, can meet the increasingly stringent requirements for refrigerants in mobile air conditioning. It has been found to be an effective refrigerant, heat transfer medium, propellant, foam forming agent, blowing agent, gaseous dielectric, sterilizing support, polymerization medium, particle separation fluid, support fluid, abrasive agent, Polishing, displacement drying agent and power cycle working fluid. Accordingly, compositions containing HFO-1234yf are among the materials being developed for use in many of the applications mentioned above. Therefore, there is a need for new manufacturing processes for the production of tetrafluoropropenes and, in particular, 2,3,3,3-tetrafluoropropene.

Several methods of preparation of HFOs are known. For example, U.S. Pat. No. 4,900,874 (Ihara et al.) Discloses a method for making fluorine containing olefins by contacting hydrogen gas with fluorinated alcohols. Although this appears to be a relatively high performance process, the commercial scale handling of high temperature hydrogen gas is dangerous. In addition, the cost of commercial production of hydrogen gas, such as the construction of a hydrogen plant in situ, is economically expensive.

U.S. Pat. No. 2,931,840 (Marquis) discloses a method for making fluorine-containing olefins by pyrolysis of methyl chloride and tetrafluoroethylene or chlorodifluoromethane. This process is a relatively low yield process, and a very large percentage of the organic starting material is converted into unwanted and / or unimportant byproducts, including a considerable amount of carbon black which tends to deactivate the catalyst used in the process .

US 20090312585 discloses a process for making 2-chloro-1,1,1,2-tetrafluoropropane by contacting 2-chloro-3,3,3-trifluoropropene with hydrogen fluoride in the presence of a catalyst, thereby Cl2 is fed in batches every 4 hours throughout the process if necessary to keep the catalyst active.

The preparation of HFO-1234yf from trifluoroacetylacetone and sulfur tetrafluoride has been described (see Banks, et al., Journal of Fluorine Chemistry, Vol. 82, Iss.2, pp. 171-174 (1997)). In addition, U.S. Pat. No. 5,162,594 (Krespan) describes a process, in which tetrafluoroethylene is reacted with another fluorinated ethylene in the liquid phase to produce a polyfluoroolefin product.

A manufacturing process for HFO-1234yf, as described in US Pat. No. 8,058,486, uses 1,1,2,3-tetrachloropropene (HCO-1230xa) as starting raw material. The process consists of the following three steps: 1) HCO-1230xHF-> 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) HCl in a vapor phase reactor loaded with a solid hydrofluorination catalyst such as fluorinated chromia, 2) HCFO-1233xf HF -> 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) in a liquid phase reactor loaded with a liquid hydrofluorination catalyst such as Fluorinated SbCls and 3) HCFC -244bb -> HFO-1234yf in a vapor phase reactor. One problem encountered in the operation of Stage 2 is the formation of 1,1,1,2,2-pentafluoropropane (HFC-245cb), which can cause a significant loss of long-term performance. Therefore, there is a need for means by which the formation of HFC-245cb can be reduced.

Summary of the invention

The present invention relates to a process for the production of 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb), which comprises reacting 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) ) with hydrogen fluoride, in a reaction vessel in the liquid phase in the presence of a hydrofluorination catalyst in the liquid phase. The invention provides an improved process for producing 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb), in which the conversion of HCFO-1233xf is maintained at more than 80%, while minimizing the formation of 1,1,1,2,2-pentafluoropropane. In another embodiment, the conversion of HCFO-1233xf is greater than about 90%, and in another embodiment, greater than about 95%. This improved conversion is effected by the periodic addition of new hydrofluorination catalyst in small increments. The addition of fresh hydrofluorination catalyst occurs continuously or periodically.

More specifically, the present method relates to a method for minimizing the formation of 1,1,1,2,2-pentafluoropropane in a liquid phase reaction of 2-chloro-3,3,3-trifluoropropene and HF in the presence of a hydrofluorination catalyst, comprising:

(a) reacting HF with a sufficient amount of 2-chloro-3,3,3-trifluoropropene in the presence of a hydrofluorination catalyst under effective conditions to form 2-chloro-1,1,1,2-tetrafluoropropane, the hydrofluorination catalyst present in sufficient amounts to catalyze said reaction, wherein the 2-chloro-1,1,1,2-tetrafluoropropane is formed with a conversion of 80% or more and wherein the selectivity of 1,1,1, 2,2-pentafluoropropane is 20% or less; Y

(b) maintaining the 2-chloro-1,1,1,2-tetrafluoropropane formed with either 80% conversion or more as well as with a selectivity of 1,1,1,2,2-pentafluoropropane of 20% or less by adding said hydrofluorination catalyst continuously or periodically in incremental amounts.

For example, in one embodiment, the formation of 1,1,1,2,2-pentafluoropropane is minimized (a) by reacting HF with a sufficient amount of 2-chloro-3,3,3-trifluoropropene in the presence of a hydrofluorination catalyst to form 2-chloro-1,1,1,2-tetrafluoropropane, the hydrofluorination catalyst being present in amounts sufficient to catalyze said reaction, wherein the 2-chloro-1,1,1,2-tetrafluoropropane is form with a conversion of 80% or more and wherein the selectivity of 1,1,1,2,2-pentafluoropropane is 20% or less; and (b) maintaining the 2-chloro-1,1,1,2-tetrafluoropropane that is formed with a conversion of 80% or more and a selectivity of 1,1,1,2,2-pentafluoropropane of 20% or less , adding said hydrofluorination catalyst periodically in an amount ranging between 0.5% and 10% by weight of the total weight of the catalyst and HF in the reactor. In one embodiment, the addition of the hydrofluorination catalyst is periodic, as described herein, while in another embodiment, the addition of the hydrofluorination catalyst is continuous.

However, there is a maximum amount of catalyst that could be added. The maximum amount added is 98% by weight with respect to the total weight of HF and catalyst.

Brief description of the drawings

The following figure is an example of the results of the procedure when performed according to the description herein. The present invention should not be construed as limited by the figure.

Figure 1 depicts the conversion of 1233xf and the selectivity of 244bb and the selectivity of 245cb over time from the periodic addition of SbCls catalyst in the liquid phase fluorination reaction of 1233xf HF-> 244b. The dark line in the figures represents the selectivity of 244bb, while the upper clear line represents the conversion to 1233xf and the line below represents the selectivity of 245cb.

Detailed description of the invention

The above general description and the following detailed description are by way of example only and explanatory and are not restrictive of the invention as defined in the appended claims. Other features and benefits of one or more of the embodiments will become apparent from the following detailed description and from the claims.

As used herein, the terms "comprising", "comprising", "including", "including", "having", "having" or any other variation thereof are intended to cover a non-exclusive inclusion. For example, a method, method, article or apparatus comprising a list of elements is not necessarily limited only to those elements, but may include other elements not expressly enumerated or inherent to said method, method, article or apparatus. In addition, unless expressly indicated otherwise, "or" refers to an inclusive or not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or is present) and B is false (or is not present), A is false (or is not present) and B is true ( or is present), and both A and B are true (or are present).

In addition, the use of "a" or "an" is used to describe elements and components described herein. This is done simply for convenience and to give a general sense of the scope of the invention. This description must be read to include one or at least one, and the singular also includes the plural, unless it is obvious that it means the opposite.

Unless defined otherwise, all technical and scientific terms and expressions used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, suitable methods and materials are described below. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety, unless a particular passage is cited. In case of conflict, this descriptive report will prevail, including definitions. In addition, the materials, methods and examples are illustrative only and are not intended to be limiting.

When a quantity, concentration or other value or parameter is given as a range, a preferred range or a list of higher preferred values and / or lower preferable values, it should be understood that all ranges formed from any pair of any type are specifically described. upper range limit or preferred value and any lower range limit or preferred value, regardless of whether the ranges are described separately. In cases where a range of numerical values is enumerated in this memory, unless stated otherwise, the interval is intended to include its endpoints, and all integers and fractions within the range.

The term "dehydrochlorine", "dehydrochlorination" or "dehydrochlorinated", as used herein, means a process during which hydrogen and chlorine are separated in adjacent carbons in a molecule.

The term "alkyl", as used herein, alone or in combination, includes cyclic or acyclic and straight or branched chain alkyl groups, such as, methyl, ethyl, n-propyl, / -propyl, or the different isomers of them. It includes, for example, straight or branched chain alkyl groups containing from 1 to 6 carbon atoms and cyclic alkyl groups containing from 3 to 6 carbon atoms of the ring and up to a total of 10 carbon atoms.

The term "hydrofluoroolefin", as used herein, means a molecule containing hydrogen, carbon, fluorine and at least one carbon-carbon double bond,

As used herein, the terms "fluorination catalyst" and "hydrofluorination catalyst" are synonymous and are used interchangeably.

The term "in small increments," as used herein, refers to the amount of hydrofluorination catalyst that is added to the reactor to maintain both the conversion of 2-chloro-3,3,3-trifluoropropene to chloro-1,1,1,2-tetrafluoropropane and the selectivity of 1,1,1,2,2-pentafluoropropane to the desired level.

By the expression "desired level" is meant that the conversion of 2-chloro-3,3,3-trifluoropropene to 2-chloro-1,1,1,2-tetrafluoropropane is at a specific objective level which varies from about 80% to about 100% conversion and that the selectivity of 1,1,1,2,2-pentafluoropropane ranges from about 20% to about 0%.

The term "periodically", or periodic or synonymous thereof, when referring to the addition of hydrofluorination catalyst as used herein, means that the hydrofluorination catalyst is added to the reactor each time when the conversion of 2-chloro -3,3,3-trifluoropropene to 2-chloro-1,1,1,2-tetrafluoropropane falls below the desired level.

The term "continuously" or "continuous", or synonymous thereof, when referring to the addition of hydrofluorination catalyst, indicates that the hydrofluorination catalyst is constantly added in small increments, obviously smaller than when the addition is periodic. The rate of addition to which the hydrofluorination catalyst is added is described herein.

The present process is an intermediate step in the preparation of 2,3,3,3-tetrafluoropropene (HFO-1234yf). It refers to the hydrofluorination of 2-chloro-3,3,3-trifluoropropene to form 2-chloro-1,1,1,2-tetrafluoropropane. The Production of 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb), in the present procedure, requires the reaction of 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) with hydrogen fluoride in a liquid phase reaction vessel and a liquid phase hydrofluorination catalyst to thereby produce HCFC-244bb. The reaction is carried out in a batch or continuous mode.

According to the process of the present invention, HCFO-1233xf is converted to 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb). In one embodiment, this step can be carried out in the liquid phase in a liquid phase reactor. In the invention, any reactor suitable for a hydrofluorination reaction can be used. The reactor is constructed of materials that are resistant to the corrosive effects of HF, such as Hastelloy-C, Inconel, Monel and containers coated with fluoropolymers. Liquid phase hydrofluorination reactors of this type are well known in the art.

In the invention, any substantially pure liquid phase fluorination catalyst can be used. By substantially pure, it means that the catalyst contains a minimum of impurities. In one embodiment, it is greater than 90% pure; in another embodiment, it is greater than 95% pure; while in another embodiment, it is greater than 98% pure. A non-exhaustive list of liquid phase fluorination catalysts includes Lewis acids, such as transition metal halides, transition metal oxides, Group IVb metal halides, Group Vb metal halides, or combinations thereof. Non-exclusive examples of liquid phase fluorination catalysts are antimony halide, tin halide, tantalum halide, titanium halide, niobium halide, molybdenum halide, iron halide, fluorinated chromium halide, fluorinated chromium oxide or combinations thereof. Specific, non-exclusive examples of liquid phase fluorination catalysts are SbCls, SbCl3, SbFs, SnCL, TaCl5, TiCl4, NbCl5, MoCl6, FeCl3, a fluorinated species of SbCls, a fluorinated species of SbCl3, a fluorinated species of SnCl4, a fluoridated species of TaCl5, a fluorinated species of TiCl4, a fluorinated species of NbCl5, a fluorinated species of MoCl6, a fluorinated species of FeCl3, or combinations thereof. In another embodiment, the fluorination catalyst is antimony pentachloride.

These catalysts can be easily regenerated by any means known in the art if they are deactivated. A suitable method for regenerating the catalyst involves flowing a stream of chlorine through the catalyst. For example, from 0.002 to 0.2 lb (0.0009 to 0.09 kg) per hour of chlorine can be added to the liquid phase reaction for each pound (kg) of liquid phase fluorination catalyst. This can be done, for example, for 1 to 2 hours or continuously at a temperature of 65 ° C to 100 ° C.

In the practice of the present invention, a liquid phase catalyst as described below is charged to a hydrofluorination reactor before heating the reactor. Then, the HF and HCFO-1233xf are fed to the reactor once the reactor reaches the desired temperature. The reaction is carried out under effective reaction conditions. For example, the reaction is carried out at a temperature ranging from 30 ° C to 200 ° C, while in another embodiment, it is carried out at a temperature ranging from 50 ° C to 150 ° C and, in another embodiment, at a temperature of temperature that varies from 75 ° C to 125 ° C. The pressure of the reaction varies depending on the temperature, the amount of hydrogen fluoride used and the conversion of HCFO-1233xf. Convenient working pressure ranges from 34 kPag (5 psig) to 1380 kPag (200 psig) in one embodiment, while in another embodiment, from 210 kPag (30 psig) to 1210 kPag (175 psig) and, in yet another embodiment, another embodiment, from 410 kPag (60 psig) to 1030 kPag (150 psig).

HF and 2-chloro-3,3,3-trifluoropropene are present in effective concentrations for conversion to 2-chloro-1,1,1,2-tetrafluoropropane. In function of the stoichiometry of the reaction, the required molar ratio of HF to HCFO-1233xf is at least equal to the number of double bonds in the organic starting material and, in another embodiment, the molar ratio of HF to HCFO-1233xf is present in an excess. In one embodiment, the molar ratio of HF to HCFO-1233xf varies from 1: 1 to 50: 1, while in another embodiment, it varies from 1: 1 to 30: 1 and, in yet another embodiment, varies from 2: 1 to 15: 1. Any water in the HF will react with the catalyst and deactivate it. Therefore, substantially anhydrous HF is preferred. By "substantially anhydrous" is meant that the HF contains about 0.05% by weight of water or less. In one embodiment, the HF contains about 0.02% by weight of water or less. However, one skilled in the art will appreciate that the presence of water in the catalyst can be compensated by increasing the amount of catalyst used.

One of the secondary products of the reaction is the formation of 1,1,1,2,2-pentafluoropropane (HFC-245cb). The objective is to minimize the formation of 1,1,1,2,2-pentafluoropropane. This objective is important for several reasons. First, the formation of 1,1,1,2,2-pentafluoropropane decreases the yield of 2-chloro-1,1,1,2-tetrafluoropropane. In addition, the formation of 1,1,1,2,2-pentafluoropropane interferes with the efficiency of the general procedure to form 2,3,3,3-tetrafluoropropene (HFO-1234yf), and a separate step must be employed to separate 1 , 1,1,2,2-pentafluoropropane from 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb), so that the latter compound can be dehydrohalogenated to form 2,3,3,3- tetrafluoropropene (HFO-1234yf) in the next step of the general procedure, as defined herein. Thus, it is important to find means of decreasing the amount of 1,1,1,2,2-pentafluoropropane formed in this reaction.

The inventors of the present invention have found that the formation of 1,1,1,2,2-pentafluoropropane is minimized if the reaction is carried out as described herein. More specifically, the formation of 1,1,1,2,2-pentafluoropropane in a liquid phase reaction of 2-chloro-3,3,3-trifluoropropene and HF in the presence of a hydrofluorination catalyst is minimized if the reaction is carried out by (a) reaction of HF with a sufficient amount of 2-chloro-3,3,3-trifluoropropene in the presence of a hydrofluorination catalyst under effective conditions to form 2-chloro-1,1,1,2- tetrafluoropropane, the hydrofluorination catalyst being present in sufficient amounts to catalyze said reaction and forming 2-chloro-1,1,1,2-tetrafluoropropane with a conversion of 80% or more and a selectivity of 1,1,1,2 , 2-pentafluoropropane of 20% or less; and (b) maintenance of 2-chloro-1,1,1,2-tetrafluoropropane formed with both a conversion of about 80% or more and a selectivity of 1,1,1,2,2-pentafluoropropane of 20% or less adding hydrofluorination catalyst continuously or periodically in increased amounts. In one embodiment, the addition of hydrofluorination catalyst is periodically as described herein, while in another embodiment the addition of hydrofluorination catalyst is continuous.

In the present process, in one embodiment, the amount of 2-chloro-1,1,1,2-tetrafluoropropane formed is monitored periodically to determine the yield of 2-chloro-1,1,1,2-tetrafluoropropane or the amount of conversion of 2-chloro-3,3,3-trifluoropropene. In one embodiment, if the yield amount of 2-chloro-1,1,1,2-tetrafluoropropane is 80% or less, additional catalyst is added to the reaction, as described herein. The amount of yield and conversion is determined by techniques known in the art, such as taking from the reactor a small aliquot of sample formed in the reaction and injecting it into a gas chromatograph and comparing the amounts of 2-chloro-1,1, 1,2-tetrafluoropropane, 1,1,1,2,2-pentafluoropropane and 2-chloro-3,3,3-trifluoropropene and any other product formed, as measured by the GC area (FID).

In another embodiment, additional catalyst is added if the yield amount or conversion to 2-chloro-1,1,1,2-tetrafluoropropane is 90% or less. In another embodiment, additional catalyst is added if the amount of yield or conversion to 2-chloro-1,1,1,2-tetrafluoropropane is 95% or less.

When additional catalyst is added, in one embodiment, it is added to the location in the reactor where the reaction takes place. In one embodiment, the reactor is added to the same side as the reactants are added. For example, if the reactants, i.e., HF and 2-chloro-3,3,3-trifluoropropene are added to the top of the reactor, the catalyst is added to the top of the reactor, i.e., charged to the reactor. upper part of the reactor.

When catalyst has to be added to the reactor, according to the present invention, it is added continuously or periodically in small increments. In one embodiment, when added in small increments as described hereinafter, it is added so that the catalyst concentration increases by 10% by weight or less, based on the total weight of the catalyst and HF in the reactor . This amount is easily determined, because the amount of catalyst and HF in the reactor is based on the amount of HF and catalyst that was added to the reactor. Thus, for example, if additional catalyst is added to the reactor, and the amount of added catalyst is 25 grams and the amount of HF added is 75 grams, the amount of catalyst to be added is less than 10 grams, which is less than 10% by weight, based on the total weight of catalyst and HF in the reactor.

In another embodiment, if the catalyst is to be added periodically, it is added in an amount of 5% by weight or less, based on the total weight of the catalyst and HF. In yet another embodiment, if the catalyst is to be added periodically, it is added in an amount of 3% by weight or less, based on the total weight of the catalyst and HF. However, if the catalyst is to be added periodically, a minimum of 0.5% by weight is added based on the total weight of the catalyst and HF in the reactor. Therefore, in one embodiment, the amount of added catalyst is 10%, 9.5%, 9%, 8.5%, 8.0%, 7.5%, 7.0%, 6.5%, 6.0%, 5.5%, 5.0%, 4.5%, 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, 1.5%, 1.0% or 0.5% by weight, based on the total weight of the catalyst and HF added to the reactor.

The amount of hydrofluorination catalyst added periodically may or may not increase each time by the same percentage with respect to the total weight of the catalyst and HF in the reactor. In one embodiment, the increase in the catalyst each time it is added is the same percentage, while in another embodiment, the increase added periodically is a different percentage. Independently, the amount of added catalyst is in the range described herein.

The amount of added catalyst each time depends on the desired level of conversion of 2-chloro-3,3,3-trifluoropropene to 2-chloro-1,1,1,2-tetrafluoropropane.

In one embodiment, the catalyst is present in an ionic liquid. Catalysts based on ionic liquids are well known in the art. See, for example, WO 2008/149011 and WO 01/81353. Catalysts based on ionic liquids are prepared by techniques known in the art. In one embodiment, the catalysts based on an ionic liquid are obtained by reaction of at least one Lewis acid halogenated or oxyhalogenated based on, for example, aluminum, titanium, niobium, tantalum, tin, antimony, nickel, zinc or iron with a salt of general Y + A-, where A- designates a halide anion, such as bromide, iodide, chloride or fluoride and Y + designates a quaternary ammonium cation, quaternary phosphonium cation or ternary sulfonium cation.

For example, antimony-based ionic liquids, such as antimony pentachloride, are prepared from the reaction product of SbOCh and tetra-n-butylammonium chloride using techniques known in the art.

The catalyst can be added in batches or continuously. If it is added continuously, in one embodiment, it is added at a rate of 0.03% by weight or less per hour, based on the total weight of the catalyst and the HF. In another embodiment, the reactor is added at a rate of 0.01% by weight per hour, and in another embodiment, it is added at a rate of 0.005% by weight per hour, based on the total weight of the HF and catalyst.

It has been found that when the catalyst is added in small increments, according to the present invention, the conversion of 2-chloro-3,3,3-trifluoropropene to 2-chloro-1,1,1,2-tetrafluoropropane is increased notably, while the selectivity to 1,1,1,2,2-pentafluoropropane remains at the desired level. In particular, it has been found that the reaction can be performed for tens or hundreds of hours while maintaining a high conversion of 2-chloro-3,3,3-trifluoropropene to 2-chloro-1,1,1,2 -tetrafluoropropane and a low selectivity of 1,1,1,2,2-pentafluoropropane. For example, using the method, according to the present invention, the conversion of 2-chloro-3,3,3-trifluoropropene to 2-chloro-1,1,1,2-tetrafluoropropane can be achieved from 80% to 98%. %, for example, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%. Furthermore, using the process according to the present process, the selectivity of 1,1,1,2,2-pentafluoropropane can vary from 20% to 0.5%, such as 20%, 19%, 18%, 17% , 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0 , 5% or less. For several tens and hundreds of hours, the reaction can reach any of these levels, whatever the desired level.

The yield of 2-chloro-1,1,1,2-tetrafluoropropane is controlled, to some extent, when additional catalyst is added. For example, the yield is higher when the catalyst is added when the selectivity to 1,1,1,2,2-pentafluoropropane is less than 5%. Therefore, a desired yield and conversion to 2-chloro-1,1,1,2-tetrafluoropropane can be controlled, to some extent, as to when the catalyst is added to the reaction.

After the reaction takes place for a period of time, the deactivation of the catalyst begins to take place, so that the conversion of 2-chloro-3,3,3-trifluoropropene into 2-chloro-1,1,1 begins to decrease. , 2-tetrafluoropropane. As deactivation of the catalyst occurs, the hydrofluorination catalyst is added to the reactor in small increments, as described herein, to maintain the conversion of HCFO-1233xf to the levels described herein. The deactivation of the catalyst means the reduction of the conversion of HCFO-1233xf over time in the stream. The catalyst can be added, in one embodiment, after the reaction is stopped (the feeds of both HF and HCFO-1233xf are stopped). In another embodiment, the catalyst is added after the reactor pressure drops somewhat. In some embodiments, the catalyst is added after the bulk of the HF inventory in the reactor is further removed. In another embodiment, the catalyst is added while the reaction is in progress. The catalyst is added so that its concentration increases in the increase as described herein.

No additional catalyst is added to the reactor when a total of 98% by weight of catalyst has been added to the reactor, based on the total weight of the catalyst and HF. The reaction is allowed to proceed until the level of conversion to 2-chloro-1,1,1,2-tetrafluoropropane is less than the desired conversion to 2-chloro-1,1,1,2-tetrafluoropropane, for example in a embodiment, when it is 80% or less, in another embodiment, 90% or less and in another embodiment, 95% or less. At this juncture, in some embodiment, the catalyst is regenerated by flowing a stream of chlorine through the catalyst. In some embodiments, the catalyst is partially or completely separated from the reactor using techniques known in the art, and new catalyst is added and / or the remaining catalyst is regenerated using techniques known in the art, for example, as described herein. .

Then the reaction restarts. When the conversion to 2-chloro-1,1,1,2-tetrafluoropropane is 80% or less, or 90% or less or 95% or less, additional catalyst is added in small increments, according to the present invention.

The inventors of the present invention have also found that the conversion amount of 2-chloro-1,1,1,2-tetrafluoropropane is increased and the amount of 1,1,1,2,2-pentafluoropropane is reduced if the hydroforation is initiated with a fluorination catalyst present at a concentration of 50% by weight or less. As defined above, the percentage by weight of catalyst is the weight percentage of the fluorination catalyst relative to the total weight of the catalyst and HF in the reactor. In another embodiment, the catalyst is initially present at 40% by weight or less, and in yet another embodiment, is present at 25% by weight or less. However, the catalyst that is present is at a minimum concentration of 2% by weight initially to effect the hydrofluorination of 2-chloro-3,3,3-trifluoropropene to 2-chloro-1,1,1,2-tetrafluoropropane. Thus, to initiate the reaction, the hydrofluorination catalyst is present in an amount ranging from 2% by weight to 50% by weight, based on the total weight of the catalyst and HF in the reactor. In another embodiment, the catalyst is initially present in an amount ranging from 10% by weight to 40% by weight, based on the total weight of the catalyst and HF in the reactor, and even in another embodiment, the catalyst is present in a amount ranging from 15% by weight to 25% by weight, based on the total weight of catalyst and HF in the reactor. For example, in one embodiment, the hydrofluorination of HCFO-1233xf is initiated with a concentration of Sb catalyst (SbCl5 as initial form) of 50% by weight or less, in another embodiment, of 40% by weight or less, and in another embodiment of 25% by weight or less, to achieve the desired initial behavior of the catalyst. The catalyst concentration is defined as the weight percentage of SbCl 5 catalyst in the total weight of SbCl 5 catalyst and HF in the reactor. The desired initial behavior of the catalyst is defined as a conversion of HCFO-1233xf of about 80% or more, in one embodiment, or 90% or more in another embodiment, and in yet another embodiment of 95% or more. Additionally, it is defined as a selectivity of HFC-245cb of 20% or less, in one embodiment, of 10% or less, in another embodiment, and of 5% or less, in yet another embodiment. When the conversion to 2-chloro-1,1,1,2-tetrafluoropropane is less than the desired amount, the catalyst concentration is then increased continuously or periodically in small increments, as described herein.

The resulting HCFC-244bb, as well as unconverted HCFO-1233xf and HF can be recovered from the reaction mixture by any method of separation or purification known in the art, such as neutralization and distillation. HCFC-244bb can be used in pure form or, optionally, in partially pure or impure form with the entire effluent from the production stage of HCFC-244bb used as an intermediate in the production of 2,3,3,3-tetrafluoropropene HFO-1234yf. The process of the invention can be carried out in a batch or continuous mode. In a continuous process, HCFO-1233xf and HF are preferably fed simultaneously to the reactor after the reactor reaches the desired temperature. The temperature and pressure of the hydrofluorination reaction remain essentially the same for the batch and continuous modes of operation. The residence time or the contact time varies from 1 second to 2 hours, preferably from 5 seconds to 1 hour and more preferably from 10 seconds to 30 minutes. A sufficient amount of catalyst must be present to effect hydrofluorination at the residence times described above. In a continuous operation mode, HF, HCFO-1233xf and HCFC-244bb are continuously separated from the reactor.

It is understood that when the catalyst is added, according to the present invention, the other parameters described above remain the same. More specifically, the temperatures, the pressures, the molar ratio of HF to HCFO-1233xf, and any other parameter discussed hereinabove are in the ranges described herein. This invention contemplates that the new catalyst to be added is the same or different from the catalyst present in the reactor, either originally or in the previous addition. However, in one embodiment, the added catalyst is the same as originally present, and in each of the catalyst additions, the added catalyst is the same as that originally present in the reactor for this reaction.

As described above, the fluorination process of the present invention is an intermediate process for preparing tetrafluoropropenes, including 2,3,3,3-tetrafluoropropene (HFO-1234yf).

Stage 1A:

CC12 = CC1CH2C1 3 HP ------ CF3CC1 = CH 2

(1,1,2,3-tetrachloroprop ene) (HC FO -1233xf)

3 HC1

Stage 1B:

c c i3c c i = c h 2 3 HF ------- ► CF3C C 1 = C H 2

(2,3,3,3-tetradoropropene) (HCFO-1233x0)

3 HC1

Stage 1C:

CC13CHC1CH, CI 3HF ------ ►

(1,1,1,2,3-pentadoropropane)

CF3C C 1 = C H 2 4 HC1

(HCFO-1233x1)

Stage 2:

CF3C C 1 = C H 2 HF ------ ► CF3CFC1CII3

(HCF0-I233xf) (HCFC-244bb)

Stage 3:

CF3CFCICH3 ------ *. CF3C F = C H 2 HCI

(HCFC-244bb) (HFO-1234yf)

In the first stage of the reaction, the chlorohydrocarbon is reacted with HF in the presence of a catalyst under fluorination conditions to produce CF3CCUCH2 (HCFO 1233xf). Three alternative reactions are provided, each with different starting materials. In a reaction, the starting material is 1,1,2,3-tetrachloropropene; in the second reaction, the starting material is 2,3,3,3-tetrachloropropene; while in the third reaction, 1,1,1,2,3-pentachloropropane is the starting material. In the third alternative, 1,1,1,2,3-pentachloropropane is not only fluorinated, but the reactant is also dehydrochlorinated to produce 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf). The second stage of the reaction is the fluorination of HCFO-1233xf in the presence of a catalyst to produce 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb). The third reaction step is the dehydrochlorination of HCFC-244bb to produce 2,3,3,3-tetrafluoropropene (HFO-1234yf).

In the second stage of the process, 2-chloro-3,3,3-trifluoropropene (1233xf) is hydrofluorinated to form 2-chloro-1.1.1.2- tetrafluoropropane (244bb), which is then dehydrochlorinated to form the refrigerant 2,3 , 3,3-tetrafluoropropene (HFO-1234yf). One of the effects of the present procedure is to minimize the formation of 1.1.1.2.2- pentafluoropropane (245cb), since the formation of 245cb interferes with and makes it more difficult to carry out the dehydrochlorination reaction to form 2,3,3, 3-tetrafluoropropene (HFO-1234yf). However, by maintaining the reaction under the reaction conditions described above, the present process minimizes the formation of 1.1.1.2.2- pentafluoropropane (245cb) and CF3CHClCH2F (1,1,1,3-tetrafluoro-2-chloropropane) and maximizes the formation of the desired product CF3CCFCH3.

Therefore, another aspect of the present process is to prepare tetrafluoropropenes, including 2,3,3,3-tetrafluoropropene (HFO-1234yf).

According to one embodiment, the present invention includes a manufacturing process for making 2,3,3,3-tetrafluoroprop-1-ene using a starting material according to formula I:

CX2 = CCFCH2X (Formula I)

CX3-CCl = CH2 (Formula II)

CX3-CHCFCH2X (Formula III)

wherein X is independently selected from F, CI, Br and I, with the proviso that at least one X is not fluorine. In certain embodiments, the compounds of Formula I contain at least one chlorine, most X as chlorine, or all X as chlorine. In certain embodiments, the compound (s) of Formula I include 1,1,2,3-tetrachloropropene (HCO-1230xa).

The method generally includes at least three reaction steps. In the first step, a starting composition of Formula I (such as 1,1,2,3-tetrachloropropene) is reacted with anhydrous HF in a first vapor phase reactor (fluorination reactor) to produce a mixture of 2. -chloro-3,3,3-trifluoropropene (1233xf) and HCl. In certain embodiments, the reaction occurs in the vapor phase in the presence of a vapor phase catalyst, such as, but not limited to, a fluorinated chromium oxide. The catalyst may (or may not) have to be activated with anhydrous hydrogen fluoride (hydrogen fluoride gas) before use, depending on the state of the catalyst.

While fluorinated chromium oxides are described as the vapor phase catalyst, the present invention is not limited to this embodiment. Any fluorination catalyst known in the art can be used in this process. Suitable catalysts include, but are not limited to, oxides, hydroxides, halides, chromium oxyhalides, aluminum, cobalt, manganese, nickel, and iron, inorganic salts thereof, and mixtures thereof, and any of which may optionally be fluorinated. In one embodiment, the catalyst is chromium oxide, such as, for example, C 2 O 3. Co-catalysts may also be present. Combinations of suitable catalysts for the first stage of fluorination include exclusively Cr2O3, FeCh / C, Cr2O3 / Al2O3, Cr2O3 / AlF3, Cr2O3 / carbon, CoCl2 / Cr2O3 / Al2O3, NiCl2 / Cr2O3 / Al2O3, CoCl2 / AlF3, NiCl2 / AlF3 and mixtures thereof . In one embodiment, the chromium oxide is present with a co-catalyst for the fluorination reaction. Chromium oxide / aluminum oxide catalysts are described in U.S. Pat. 5,155,082. Chromium catalysts are also disclosed in U.S. Pat. No. 3,258,500. In another embodiment, the chromium (III) oxides, such as crystalline chromium oxide or amorphous chromium oxide, are used as catalysts, while in another aspect of the present invention, the catalyst for this fluorination step is the amorphous chrome. One such chromium oxide catalyst that is used in the first fluorination step is the activated chromium oxide gel catalyst, described in US Pat. No. 3,258,500. Chromium oxide (Cr2O3) is a commercially available material that can be purchased in a variety of particle sizes.

The first fluorination reaction, according to the present invention, can be carried out under atmospheric pressure. In another embodiment, this reaction can be carried out at pressures less than or greater than atmospheric pressures. For example, the process can be carried out, in one embodiment, at a pressure ranging from 0 kPag (0 psig) to 1380 kPag (200 psig) and in another embodiment, from 14 kPag (2 psig) to 1030 kPag ( 150 psig) and in another embodiment from 34 kPag (5 psig) to 690 kPag (100 psig).

The first fluorination reaction is carried out under conditions effective for conversion to 1233xf. In one embodiment, the process temperature may vary from 150 ° C to 400 ° C, in another embodiment from 180 ° C to 400 ° C. In another embodiment, the process temperature varies from 180 ° C to 400 ° C, while in another embodiment, the process temperature is carried out from 200 ° C to 300 ° C.

When the compound of formula I is 1,1,2,3-tetrachloropropene (HCO-1230xa), the molar ratio of HF to 1230xa in step 1 of the reaction varies from 1: 1 to 50: 1 and, in certain embodiments , from 10: 1 to 20: 1. The reaction between HF and HCO-1230xa is carried out at a temperature of 150 ° C to 400 ° C (in certain embodiments, from 180 ° C to 300 ° C) and at a pressure of 0 kPag (0 psig) to 1380 kPag ( 200 psig) (in certain embodiments from 34 kPag (5 psig) to 690 kPag (100 psig). The contact time of 1230x with the catalyst can vary from 1 second to 60 seconds, however, longer times can be used or shorter.

The second step of the process is the hydrofluorination of 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), as described herein, to form 2-chloro-1,1,1,2-tetrafluoropropane ( HCFC-244bb). Typically, the 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) produced is first recovered from the product mixture and then used as a raw material for the next step.

The third step of the present process is the dehydrochlorination of 2-chloro-1,1,1,2-tetrafioropropane (HCFC-244bb). In the third stage of the production of 1234yf, 244bb is fed to a second steam phase reactor (dehydrochlorination reactor) to be dehydrochlorinated to prepare the desired product 2,3,3,3-tetrafluoroprop-1-ene (1234yf ). This reactor contains a catalyst that can catalytically dehydrochlorinate HCFC-244bb to produce HFO-1234yf.

The catalysts can be metal halides, halogenated metal oxides, neutral metals (or zero oxidation state) or metal alloys, or activated carbon in bulk or in supported form.

The metal halide or metal oxide catalysts may include, but are not limited to, metal halides, mono-, bi, and tri-valent oxides, and mixtures thereof. Component metals include, but are not limited to C r, Fe3 +, Mg2 +, Ca2 +, Ni2 +, Zn2 +, Pd2 +, Li +, Na +, K + and Cs +. Halogen components include, but are not limited to F-, CI-, Br- and I-. Examples of useful mono- or bi-valent metal halides include, but are not limited to LiF, NaF, KF, CsF, MgF2, CaF2, LiCl, NaCl, KCl and CsCl. Halogenation treatments may include any of those known in the prior art, particularly those employing HF, F2, HCl, Cl2, HBr, Br2, HI and I2 as a source of halogenation.

When they are neutral, that is, of zero valence, metals, metal alloys and their mixtures are used. Useful metals include, but are not limited to Pd, Pt, Rh, Fe, Co, Ni, Cu, Mo, Cr, Mn, and combinations of the above as alloys or mixtures. The catalyst can be supported or not supported. Useful examples of metal alloys include, but are not limited to SS 316, Monel 400, Inconel 825, Inconel 600 and Inconel 625. In one embodiment, the dehydrochlorination can be carried out in a reactor made of the alloys mentioned above without the addition of solid catalysts.

The dehydrochlorination reaction is carried out under effective conditions. In some embodiments of this invention, 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) is carried out at a temperature of 200 ° C to 700 ° C to produce a mixture of products comprising 2, 3,3,3-tetrafluoropropene (HFO-1234yf). In another embodiment, the reaction temperature for the dehydrochlorination reaction is 300 to 550 ° C. In one embodiment, the reaction pressure varies from 0 kPag (0 psig) to 1030 kPag (150 psig).

The effluent from the reactor can be fed to a caustic scrubber or to a distillation column to separate the by-product from HCl, to produce an acid-free organic product that can optionally be subjected to further purification using one or any combination of purification techniques. which are known in the art.

In some embodiments of this invention, the dehydrochlorination process is carried out by reacting 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) with a basic aqueous solution to produce a mixture of products comprising 2,3,3,3-tetrafluoropropene (HFO-1234yf). As used herein, the basic aqueous solution is a liquid that is primarily an aqueous liquid having a pH of more than 7; The liquid can be a solution, dispersion, emulsion, suspension or similar. In some embodiments of this invention, the basic aqueous solution has a pH of 8 or higher. In some embodiments of this invention, the basic aqueous solution has a pH of 10 or higher. In some embodiments of this invention, an inorganic base is used to form the basic aqueous solution. Said inorganic base can be selected from the group consisting of hydroxide, oxide, carbonate and phosphate salts of alkaline, alkaline earth metals and mixtures thereof. In some embodiments, said inorganic base is sodium hydroxide, potassium hydroxide or mixtures thereof. In some embodiments of this invention, the aqueous solution of basic character is an aqueous solution of a quaternary ammonium hydroxide of the formula NR4OH, wherein each of the R is independently hydrogen, a C1 to C16 alkyl group, an aralkyl group or a substituted alkyl group, with the proviso that not all R are hydrogen. Examples of NR4OH compounds useful in this invention are tetra-n-butylammonium hydroxide, tetra-n-propylammonium hydroxide, tetraethylammonium hydroxide, tetramethylammonium hydroxide, benzyltrimethylammonium hydroxide, hexadecyltrimethylammonium hydroxide, and choline hydroxide. Optionally, 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) is reacted with the aqueous solution of basic character in the presence of an organic solvent. In some embodiments of this invention, the organic solvent is selected from the group consisting of benzene and its derivatives, alcohols, alkyl and aryl halides, alkyl and aryl nitriles, alkyl, alkoxy and aryl ethers, ethers, amides, ketones, sulfoxides, phosphate esters and mixtures thereof. Optionally, 2-chloro-1,1,2-tetrafluoropropane (HCFC-244bb) is reacted with the basic aqueous solution in the presence of a phase transfer catalyst. As used herein, a phase transfer catalyst is intended to mean a substance that facilitates the transfer of ionic compounds to an organic phase from an aqueous phase or from a solid phase. The phase transfer catalyst facilitates the reaction between water-soluble and water-insoluble reaction components. In some embodiments of this invention, the phase transfer catalyst is selected from the group consisting of crown ethers, onium salts, cryptands, polyalkylene glycols and mixtures and derivatives thereof. The phase transfer catalyst can be ionic or neutral.

The reactors, gaskets, distillation columns and their associated feeding lines, effluent lines and associated units used in the application of the methods of embodiments of this invention can be constructed of corrosion resistant materials. Typical building materials include Teflon ™ materials and glass. Typical construction materials also include stainless steels, particularly austenitic steels, the well-known nickel-containing alloys, such as Monel ™ nickel-copper alloys, Hastelloy ™ nickel-based alloys, and nickel-chrome alloys. Inconel ™ and copper-coated steel.

The following are examples of the invention and should not be construed as limiting.

EXAMPLE 1

(Reference Example)

A liquid-phase reactor coated with Teflon ™ (Teflon is a registered trademark of EI du Pont de Nemours & Co.) equipped with a 2-inch ID catalyst separator (a column packed to prevent the catalyst from being used) was used. escape from the reactor system) for the next two experiments. The reactor dimension is 2.75 inches (6.98 centimeters) of ID x 36 inches (91.4 centimeters) of L (length).

520 grams of SbCls catalyst and 5 pounds (2.25 kg) of HF were added to the reactor to provide a catalyst concentration of about 19% by weight. The reactor was heated to 87-90 ° C at a pressure of 690 kPag (100 psig) when the HF and organic component feeds were started. The organic components (feed of HFC-245cb of 2.0% area per GC, HCFC-244bb of 5.0% area per GC and HCFO-1233xf of 92.9% area per GC) were fed on the basis of 0.6 lb / h (0.27 kg / h) and the HF was 0.4 lb / h (0.18 kg / h). The reaction was carried out under these conditions for approximately 10 hours. Samples of the reactor effluent were taken after the scrubber a total of 9 times during the experiment. The amount of HFC-245cb produced was reduced from initially about 7.0% area per GC to finally 4.9% area per GC, and the amount of unconverted HCFO-1233xf was reduced slightly from the initially area of 6.5% GC to finally 4.7% area per GC, indicating that the behavior of the catalyst gradually improved over time in the current.

COMPARATIVE EXAMPLE 1

The same liquid phase reactor as described in Example 1 was used. 4175 grams of SbCl 5 and 5 pounds (2.25 kilograms) of HF were added to the reactor to provide a concentration of ~ 65% by weight of catalyst. The organic feed (feed of HCFO-1233xf of 98% area by GC) was fed at a rate of 0.408 lb / h (0.18 kg / h) and the HF was 0.495 lb / h (0.22 kg / h) . The temperature range of the reactor for the experiment was 78-91 ° C and the pressure range was 586 kPag-793 kPag (85 psig-115 psig). The reaction was carried out continuously for approximately 136 hours. As in the first experiment, samples were taken from the reactor effluent after the scrubber for GC analysis. The results show, after 2.5 h in operation, that the conversion of HCFO-1233xf was 97.7% and the selectivities to HFC-245cb and HCFC-244bb were 40.2 and 52.8%, respectively.

In summary, the results of Example 1 and Comparative Example 1 show that the initial concentration of the catalyst has a significant impact on the initial selectivity of HFC-245cb and the initial low selectivity of HFC-245cb can be realized using a low catalyst concentration.

EXAMPLE 2

The same liquid phase reactor as described in Example 1 was used. 0.98 kg of SbCl5 catalyst was charged and 7 pounds (3.15 kg) of HF were added during the catalyst fluorination step. Hydrofluorination of HCFO-1233xf was then initiated under conditions of 85-90 ° C, 690 kPag (100 psig) and average feed rates of 0.5-0.6 lb / h (0.22-0.27 kg / h) org and 0.3-0.4 lb / h (0.13-0.18 kg / h) of HF (molar ratio of approximately 4/1 HF / HCFO-1233xf). After 37 hours in the stream, 0.19 kg of freshly prepared SbCl5 catalyst was loaded into the upper part of the reactor, which raised the catalyst concentration from 24% to 27% initially, which represents an increase of about 3%. Then the reaction was restarted. GC analysis of reactor effluent samples indicates that the conversion of HCFO-1233xf increased from approximately 36.6% (at 36 hours) to approximately 94.8% (at 38 hours) after loading by the 0.19 kg top of freshly prepared SbCls catalyst, while the selectivity of HFC-245cb only increased slightly from about 0.04% to about 1.32%. After 228 hours in operation, 0.06 kg of freshly prepared SbCls catalyst was charged from the top of the reactor, which raised the catalyst concentration from an earlier amount of 27% to 28%, which represents an increase of approximately 1%. Then the reaction was restarted. GC analysis of reactor effluent samples indicated that HCFO-1233xf conversion increased from approximately 78.5% (at 229 hours) to 94.5% (at 232 hours) after top loading of 0.06 kg of freshly prepared SbCl5 catalyst, while the selectivity of HFC-245cb only slightly increased from about 0.08% to about 0.16%.

COMPARATIVE EXAMPLE 2

The same liquid phase reactor as described in Example 1 was used.

0.86 kg of SbCl5 catalyst was charged and 7 pounds (3.15 kg) of HF were added during the catalyst fluorination step. Hydrofluorination of HCFO-1233xf was then initiated under conditions of 85-90 ° C, 690 kPag (100 psig) and average feed rates of 0.5-0.6 lb / h (0.22-0.27 kg / h) org and 0.3-0.4 lb / h (0.13-0.18 kg / h) of ^h F (molar ratio ~ 4/1 of HF / HCFO-1233xf). After 110 hours in operation, 0.62 kg of freshly prepared SbCl5 catalyst was loaded into the top of the reactor, raising the catalyst concentration from ~ 21% to ~ 35%, an increase of almost 14% . Then the reaction was restarted. The GC analysis of reactor effluent samples indicates that the conversion of HCFO-1233xf was increased from ~ 71.4% (at 108 hours) to 96.5% (at 111 hours) after loading by the of 0.62 kg of freshly prepared SbCl5 catalyst, while the selectivity of HFC-245cb only increased slightly from 0.1% to 21.6%.

In summary, the results of Example 2 and Comparative Example 2 show the strong increase in the selectivity of HFC-245cb when the top loading catalyst can be avoided using a small rate of catalyst increase.

EXAMPLE 3

A liquid phase reactor coated with Teflon ™ (Teflon is a registered trademark of EI du Pont de Nemours & Co.) equipped with a 2-inch ID catalyst separator (one column) was used. packaged to prevent the catalyst from escaping from the reactor system) for the following experiments. The reactor dimension is 3.75 inches (9.52 cm) of ID x 36 inches (91.4 cm) of L (length) and is equipped with a slow RPM stirrer. The reactor was heated by applying steam to a jacket surrounding the reaction vessel.

Initially, 675 grams of SbCls and 2725 grams of anhydrous HF (20% by weight of SbCls) were charged to the reactor and stirred slowly. The reactor was then heated with steam at about 90 ° C at a pressure of about 690 kPag (100 psig). A continuous feed of anhydrous HF was started at a rate of approximately 0.4 lb / h (0.18 kg / h) followed by a continuous feed of HCFO-1233xf at a rate of approximately 0.9 lb / h (0, 4 kg / h). The reaction products and some unreacted HF were continuously let out from the top of the catalyst separator column where they were analyzed periodically by GC. The selectivity of 245cb was initially 23%, falling to <5% in the space of 128 hours and to <2% in the space of 180 h. The conversion at 1233xf was initially about 97% and remained relatively stable (96.6% on average) during the first 350 h, at which time it began to gradually decrease, but notably and after 400 hours the rate of decrease was I accelerate even more. The average 1233xf conversion for the initial portion of 468 hours of the operation was 95.97%, while the mean selectivities of 245cb and 244bb were 3.80% and 96.14%, respectively.

After 469 h, when the conversion of 1233xf had decreased to approximately 92% to 109 grams of SbCl 5, the charge from the top was added to the reactor without disinventing the reactor. Upon restart, the conversion of 1233xf was initially 96.4% and the selectivity of 245cb was triggered at 2.0% and each gradually decreased throughout this part of the operation. The reactor was in operation for 230 hours after the first loading by the top of the catalyst before the conversion of 1233xf decreased below 92%. The conversion of 1233xf average 95.1% and the selectivities of 245cb and 244bb averaged 0.62% and 99.36%, respectively, for the 230 hours. Continuous feeds of anhydrous HF at a rate of approximately 0.4 lb / h (0.18 kg / h) and of HCFO-1233xf at a rate of approximately 0.9 lb / h (0.4 kg / h) were maintained together with the original reaction temperature and pressure. At this point, the total running time for the experiment was 699 hours.

After 699 h, when the conversion of 1233xf had decreased to approximately 92% to 101 grams of SbCl 5, the charge from the top was added to the reactor without disinventing the reactor. The 1233xf feed that did not contain 1232xf was initially used as a feed after loading by the top of the catalyst. When restarting, the conversion at 1233xf was initially 96.5% and the selectivity of 245cb was triggered at 1.5% and each gradually decreased throughout this part of the operation. The reactor was in operation for 162 hours after the second charge through the top of the catalyst before the conversion of 1233xf decreased below 92%. The conversion of 1233xf average 95.1% and the selectivities of 245cb and 244bb averaged 0.65% and 99.32%, respectively, for the 162 hours. Continuous feeds of anhydrous HF at a rate of approximately 0.4 lb / h (0.18 kg / h) and of HCFO-1233xf at a rate of approximately 0.9 lb / h (0.4 kg / h) were maintained along with the original reaction temperature and pressure. The total running time for the experiment was 861 hours at this point.

After 861 h, when the conversion of 1233xf had decreased to approximately 92% to 109 grams of SbCl 5, the charge from the top was added to the reactor without disinventing the reactor. When restarting, the conversion at 1233xf was initially 96.4% and the selectivity of 245cb was triggered at 1.3% and each gradually decreased throughout this part of the operation. The reactor was in operation for 166 hours after the third charge through the top of the catalyst before the conversion of 1233xf decreased below 92%. The conversion of 1233xf average 95.0% and the selectivities of 245cb and 244bb averaged 0.55% and 99.42%, respectively, for the 166 hours. Continuous feeds of anhydrous HF at a rate of approximately 0.4 lb / h (0.18 kg / h) and of HCFO-1233xf at a rate of approximately 0.9 lb / h (0.4 kg / h) were maintained along with the original reaction temperature and pressure. The total running time for the experiment was 1027 hours at this point.

After 1027 h, when the conversion of 1233xf had decreased to approximately 92% to 124 grams of SbCl 5, the charge from the top was added to the reactor without disinventing the reactor. When restarting, the conversion at 1233xf was initially 96.4% and the selectivity of 245cb was triggered at 2.1% and each gradually decreased throughout this part of the operation. The reactor was in operation for 226 hours after the fourth load on the top before the conversion of 1233xf decreased below 92%. The conversion of 1233xf average 95.15% and the selectivities of 245cb and 244bb averaged 0.81% and 99.16%, respectively, for the 230 hours. Continuous feeds of anhydrous HF at a rate of approximately 0.4 lb / h (0.18 kg / h) and of HCFO-1233xf at a rate of approximately 0.9 lb / h (0.4 kg / h) were maintained along with the original reaction temperature and pressure. The total running time for the experiment was 1253 hours. The conversion in 1233xf, the selectivity data for the main products, 245cb and 244bb, and the events that occurred during the experiment can be found in Figure 1.

EXAMPLE 4

The same reactor as that used for Example 3 is used for a second experiment. 715 grams of SbCl5 and 2850 grams of anhydrous HF are initially charged to the reactor (20% by weight of SbCl5) and stirred slowly. Then, the reactor is heated with steam at 90 ° C at a pressure of about 690 kPag (100 psig). A continuous feed of anhydrous HF is started at a rate of approximately 0.5 lb / h (0.22 kg / h), followed by a continuous feed of HCFO-1233xf at a rate of approximately 1.1 lb / h (0 , 49 kg / h). The reaction products and some unreacted HF were continually released from the top of the catalyst separator column where they were analyzed periodically by GC. The selectivity of 245cb is initially 21%, falling to <5% in the space of 140 hours and to <2% in the space of 205 hours. In contrast, as the selectivity of 245cb decreases, the selectivity of 244bb increases from about 78.5% to> 98%. The conversion at 1233xf is initially approximately 97.3% and remains relatively stable (97% on average) during the first 205 h. At this point, a continuous co-feed of freshly prepared SbCl 5 catalyst at a rate of about 0.6 grams / hr is started and fed into the reactor vapor space. With this rate of addition of catalyst, the selectivity of 245cb is maintained at <2%, while the conversion of 1233xf remains constant at approximately 97% during the next 500 hours that the experiment is carried out.

Claims (9)

1. A method for minimizing the formation of 1,1,1,2,2-pentafluoropropane in a liquid phase reaction of 2-chloro-3,3,3-trifluoropropene and HF in the presence of a hydrofluorination catalyst, which includes: (a) reacting HF with a sufficient amount of 2-chloro-3,3,3-trifluoropropene in the presence of a hydrofluorination catalyst under effective conditions to form 2-chloro-1,1,1,2-tetrafluoropropane, the hydrofluorination catalyst present in sufficient amounts to catalyze said reaction, and 2-chloro-1,1,1,2-tetrafluoropropane is formed with both a conversion of 80% or more and the selectivity of 1,1,1,2, 2-pentafluoropropane is 20% or less; Y (b) maintaining the 2-chloro-1,1,1,2-tetrafluoropropane formed with both a conversion of 80% or more as and a selectivity of 1,1,1,2,2-pentafluoropropane of 20% or less by adding said hydrofluorination catalyst continuously or periodically to the reactor in small increments. 2. The method according to claim 1, wherein the hydrofluorination catalyst is periodically added in an amount ranging from 0.5% by weight to 10% by weight, based on the total weight of the hydrofluorination catalyst and HF. present in the reactor, preferably in which the catalyst is periodically added in an amount ranging from 1% by weight to 5% by weight or less, based on the total weight of HF and catalyst in the reactor, and more preferably in the that the catalyst is periodically added in an amount ranging from 2% by weight to 3% by weight, based on the total weight of HF and catalyst in the reactor. The method according to claim 1 or claim 2, wherein the initial catalyst concentration in step (a) ranges from 2% by weight to 50% by weight, based on the total weight of catalyst and HF in the reactor, preferably in which the initial concentration of catalyst in step (a) ranges from 10% by weight to 40% by weight, based on the total weight of catalyst and HF in the reactor, and more preferably in which The initial catalyst concentration in step (a) ranges from 15% by weight to 25% by weight, based on the total weight of catalyst and HF in the reactor. 4. The method according to any preceding claim, wherein the hydrofluorination catalyst is antimony halide, a halide of stannous, a halide of tantalum, a halide of titanium, a halide of niobium and halide of molybdenum, a halide of iron, a fluorinated chromium halide, a fluorinated chromium oxide or combinations thereof, preferably wherein the hydrofluorination catalyst is SbCU, SbCU, SbFs, SnCU, TaCU, TiCU, NbCl5, MoCl6, FeCl3, a fluorinated species of SbCls , a fluorinated species of SbCU, a fluorinated species of SnCU, a fluoridated species of TaCU, a fluoridated species of TiCU, a fluorinated species of NbCU, a fluorinated species of MoCl6, a fluorinated species of FeCU, or a combination thereof, and more preferably wherein the hydrofluorination catalyst is SbCl5. The method according to any preceding claim, wherein the reaction is carried out at a temperature ranging from 30 ° C to 200 ° C, preferably in which the reaction is carried out at a temperature varying from 50 ° C to 150 ° C, and more preferably in which the reaction is carried out at a temperature ranging from 75 ° C to 1252 ° C. The method according to any preceding claim, wherein the reaction is carried out at a pressure ranging from 34 kPag (5 psig) to 1380 kPag (200 psig), preferably in which the reaction is carried out at a pressure ranging from 210 kPag (30 psig) to 1210 kPag (175 psig), and more preferably in which the reaction is carried out at a pressure ranging from 410 kPag (60 psig) to 1030 kPag (150 psig) ). The method according to any preceding claim, wherein the molar ratio of HF to 2-chloro-3,3,3-trifluoropropene ranges from 1: 1 to 50: 1, preferably wherein the molar ratio of HF 2-chloro-3,3,3-trifluoropropene ranges from 1: 1 to 30: 1, and more preferably in which the molar ratio of HF to 2-chloro-3,3,3-trifluoropropene varies from 2: 1 to 15: 1. 8. A method for preparing 2,3,3,3-tetrafluoroprop-1-ene, comprising: (a) providing a starting composition comprising at least one compound having a structure selected from Formulas I, II and III: CX2 = CCUCH2X Formula I CX3-CCUCH2 Formula II CX3-CHCUCH2X Formula III, wherein X is independently selected from F, CI, Br and I, with the proviso that at least one X is not fluorine; (b) contacting said starting composition with a first hydrofluorinating agent to produce a first intermediate composition comprising 2-chloro-3,3,3-trifluoropropene; (c) reacting 2-chloro-3,3,3-trifluoropropene to form 2-chloro-1,1,1,2-tetrafluoropropane according to the method set forth in any of claims 1 to 7; and (d) dehydrochlorinating 2-chloro-1,1,1,2-tetrafluoropropane to produce a reaction product comprising 2,3,3,3-tetrafluoroprop-1-ene. The method according to any preceding claim, wherein the hydrofluorination catalyst is added continuously at a rate of 0.03% by weight or less per hour based on the total weight of the catalyst and HF, preferably on the that the hydrofluorination catalyst is added at a rate of 0.01% by weight or less per hour, based on the total weight of the catalyst and HF, and more preferably in which the hydrofluorination catalyst is added at a rate of 0.005% by weight or less per hour, based on the total weight of the catalyst and HF.